Antenna system



Sept. 3, 1940.- K KOSCHMEDER 2,213,282

ANTENNA SYSTEM Kaff Masc/mieder Sept. 3, 1940. K. KoscHMlEDER Y ANTENNASYSTEM Filed March 14, 1959 2 Sheets-Sheet 2 fu/1 ffm/feder PatentedSept. 3, 1940 ANTENNA SYSTEM Kurt Koschmieder, Falkensee,East-Havelland,

Germany, assigner to C. Lorenz Aktiengesellschaft, Berlin- Tempelhof,Lorenzweg, Germany,

Application March 14, 1939, Serial No. 261,767 lln Germany April 2, 19382 Claims;

This invention relates to antenna systems, and more particularly toimprovements in that type of systems which is intended to exclusivelyrespond to vertically polarized waves.

It is Well known for the purpose of eliminating direction finding errorscaused by the night or twilight effect to design antenna systems fromthe viewpoint that merely the vertically polarized but not thehorizontally polarized waves shall 10 be picked up by the antennasystem, Antenna systems involving the aforesaid properties consist of aplurality of individual vertical antennae combined to suitable systemsby means of horizontal conductor lines. These vertical antennae 15 mayeither be dipoles, lthe so-called H-Adcocks, or half dipoles, theso-called U-Adcocks, which cooperate with earth or with a counterpoise.

This invention has for its object to provide CFI means in order toimprove the properties of the .0 last mentioned type of antenna systems,that is,

the lll-Adcock antenna.

In antenna systems of the above mentioned type, only the verticalantennae become eifective, while the energization of the horizontalinterconnecting conductor lines is either avoided or even nulliled. Twotypes of interconnecting lines are generally employed for this purpose,namely either single conductor lines or two-wire conductor lines. Thesingle conductor lines may be provided with shieldings in order toprevent undesired energization thereof and to protect such lines againstextraneous effects of radiation, while the currents flowing in theindividual conductors of a two-wire line are rendered equal in magnitudebut opposite in phase to so neutralize each other.

My invention consists in certain features of novelty which will bereadily understood from the following description and be pointed out inthe appended claims, reference being had to the accompanying drawings,in which Figs. l and 2 schematically show two antenna arrangements ofconventional type, Fig. 3 schematically shows one embodiment accordingto my invention, While Fig. l is a modification over the arrangementshown in Fig. 3.

The Fig. 1 shows a known U-Adcock antenna array comprising the verticalantennae VI and V2 which are combined to an antenna system D by means ofthe shielded horizontal single conductor lines Hi and H2 and theintermediate goniameter eld coil F. Each of the horizontal lines Hl andH2 is provided with a grounded shielding member Sl and S2, respectively,as protection against undesired extraneous influ- (Cl. Z50-33) ences.The ground connections of these shieldings are indicated at E l, E2 andIn order to impart directional effects to the antenna systems, a secondsimilar antenna system (not shown) is arranged at right angles to thefirst 5 mentioned system. Nevertheless, experience teaches that theabove mentioned precautions are insuicient to avoid directional findingerrors due to the fact that it has not been possible to reliablysuppress the horizontal polarization. Careful investigations have proventhat a capacitive coupling is set up between the vertical antennae Vland V2 and the appertaining line HI and H2, respectively, which couplingcauses the aforementioned horizontal polarization. Such capacitivecouplings are indicated inV Fig. 1 as virtual condensers Cl and C2 forillustration.

Attempts have been made in order to eliminate this capacitive couplingphenomenon, by submerging the interconnecting horizontal lines in theearth, in contradiction to the lines HI and H2 in Fig. 1 which areplaced above the earths surface. However, even in this case considerablehorizontal components have been observed since in the first instancehorizontally polarized waves still influence the submerged and shieldedlines, and on the other hand waves reflected from the earths surfaceaffect the antennae VI and V2 subsequent to a polarization changeimparted to these Waves.

My invention has for its object to reliablyl eliminate the heretoforementioned diiiculties. This is realized according to the main featurethereof by spacing each vertical antenna apart from the earths surfaceat a given distance and by the provision of shielding means even for thevertical conductors which serve for connecting the horizontal conductorlines with the lower end of the antenna in its elevated position.

'Ihe Figs. 3 and 4 show two different ways for 40 carrying out myinvention. These two embodi. ments involve the only difference that thehorizontal interconnecting lines Hl and H2 and their shieldings Sl andS2 are arranged at a certain 45 space above the ground as illustrated inFig. 3, while being submerged in the earth as shown in Fig. 4. Thevertical antennae Vl and V2 are positioned at a given distance above theearths surface and vertical portions Ll and L2 of the o interconnectinglines are connected to the lower end of these antennae. Each verticalline portion Ll and L2 is provided with a shielding AI and A2,respectively. These shieldings principally correspond to those of thehorizontal interconnecting lines and may be directly connectedtherewith. It is of course possible to ernploy suitably shielded cablelengths between the lower end of each antenna and the goniometer coil F.The length h of each of the Vertical shieldings Al and A2 between thelower end of each antenna and thelearths surface may be equal to thehalf or to the whole distance between the antennae Vl and V2.

The above described arrangement according to my invention is capable ofconsiderably reducing capacitive coupling effects between the horizontallines and the vertical antennae. Moreover, the vertical antennae arerendered substantially immune against waves being reflected from theearths surface.

The means as disclosed in the foregoing merely by the way of fewexamples in connection with shielded single-wire lines are likewiseapplicable to antenna systems employing two-conductor lines forinterconnecting the various vertical antennae. Moreover, my invention isapplicable to transmitting as well as to receiving antenna systems.

What is claimed is:

1. An antenna system comprising a plmality of vertical antennae spacedapart from one another and having their lower end spaced at a distancefrom the earths surface, horizontal conductor lines for interconnectingthe said vertical antennae to form a directional antenna system, shieldsfor said horizontal conductor lines, vertical conductor lines forconnecting each ver- KURT KOSCHMIEDER.

